Efficiency Enhancement of Top Emission Organic Light-Emitting Diodes with Ni/Au Periodic Anode

Abstract

The triple-metal-layer periodic structures in the anode for top-emission organic light-emitting diodes (TEOLEDs) are reported in this paper. The anode consists of aluminum (Al) and nickel/gold (Ni/Au) periodic structures. The Al is used for high reflectivity and Ni/Au for high work function by enhancing the hole injection from the anode into the organic hole injection layer. The Ni and Au work functions were measured at 5.3 and 5.1 eV, respectively, which were higher than that of a single Al layer at 4.2 eV. This two pair Ni/Au anode device exhibits high reflectivity and reveals the microcavity effect to increase luminescence efficiency. The optimum current efficiency with the two pair Ni/Au anode is increased to 7.99 cd/A compared with the one pair Ni/Au anode (6.85 cd/A) and three pair Ni/Au anode (5.07 cd/A).

High‐Performance Ultraviolet Photodetectors Enabled by van der Waals Schottky Junction Based on TiO2 Nanorod Arrays/Au‐Modulated Ti3C2Tx MXene

“…The WFs of MXene samples before and after contacting with the Au thin‐film substrate are measured by Kelvin probe force microscopy (KPFM), as shown in Figure 2g,h. The WF can be calculated from the contact potential difference ( V CPD ) based on the equation $${V_{{\rm{CPD}}}}\; = \;\frac{{{\Phi _{{\rm{sample}}}} - {\Phi _{{\rm{tip}}}}}}{q}$$, [ 36 ] where Φ sample is the WF of the sample, Φ tip is the WF of the probe, q is the elementary charge, and the reference material is Au (WF of ≈5.1 eV [ 37 ] ). The dark and white arrows in Figure S3a (Supporting Information) represent the V CPDs of the probe with Ti 3 C 2 T x MXene and Si substrate, corresponding to 630 and 665 mV, respectively.…”

“…[18] The WFs of MXene samples before and after contacting with the Au thin-film substrate are measured by Kelvin probe force microscopy (KPFM), as shown in Figure 2g,h. The WF can be calculated from the contact potential difference (V CPD ) based on the equation CPD sample tip V q = Φ −Φ , [36] where Φ sample is the WF of the sample, Φ tip is the WF of the probe, q is the elementary charge, and the reference material is Au (WF of ≈5.1 eV [37] ).…”

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils

“…In recent years there have been many reports of glass-based top-emissive OLEDs with good performance where Ag, 7,8 Al/Ag, 9,10 LiF/Al 12 and LiF/Al/Ag [12][13][14][15][16] have been applied as the transparent cathode, often in combination with a capping layer such as N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB), [10][11][12][13][14][15][16][17] N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD), 9 tris(8-hydroxyquinolinato)aluminium (AlQ3) 3 , 17,18 tin-doped indium oxide (ITO), SiO 2 , 15 or ZnSe. 16,19 With this second metal electrode, a microcavity resonator is obtained that amplifies a specific wavelength range and particular emission angles 15,20,21 (acting like a Fabry-Pérot filter).…”